This invention relates to electronic timepieces, and more particularly to electronic timepieces having a semiconductor sensor to measure temperature and pressure.
An example of such an analog quartz electronic timepiece is Japanese Patent Publication No. 61-52955, wherein the integrated circuit chip of the sensor is mounted on a substrate which is applied directly on the base frame. The substrate is affixed to the frame by a circuit securing plate anchored to the base by screws. This results in securing most of the circuit substrate.
The construction utilized in the prior art electronic timepieces has been satisfactory, however it suffers from the disadvantage that the supporting substrate invariably bends to some degree. This is due to changes in the height of the plate, and thickness of the circuit substrate and supporting plate, substrate warpage and changes in screw pressure. When the substrate bends, the IC chip also bends slightly due to being bonded to the circuit substrate. When a semiconductor sensor is built into the IC chip, any bending of the IC chip causes changes in channel length and/or the channel width of the transistor forming the sensor. This causes changes in the properties of the sensor even when the degree of bending is minute.
When the clamping force of the screw securing the circuit substrate to the supporting plate changes due to variations in temperature, vibrations or the like, the bending of the circuit substrate around the IC chip produces large changes in sensor properties. This occurs even if an offset adjustment or inclination adjustment for the sensor is made. As a result of such bending, the properties of the sensor vary from the initial condition set by the manufacturer. Such a change in properties greatly affects the accuracy of the timepiece over time.
Accordingly, it is desirable to provide a mount for a semiconductor sensor in an electronic timepiece to overcome the shortcomings of the prior art described above.